The suitability of an uncemented hydroxyapatite coated (HAC) hip hemiarthroplasty stem for intra-capsular femoral neck fractures in osteoporotic elderly patients: the Metaphyseal-Diaphyseal index, a solution to preventing intra-operative periprosthetic fracture
1 Department of Trauma & Orthopaedics, Queen Elizabeth Hospital, South London Healthcare NHS Trust, Stadium Road, Greenwich, London, SE18 4QH, UK
2 Department of Trauma & Orthopaedics, Princess Royal University Hospital, South London, Healthcare NHS Trust, Farnborough Common, Orpington, BR6 8ND, Kent, UK
3 Department of Trauma & Orthopaedics, Darent Valley Hospital, Darenth Wood Road, Dartford, DA2 8DA, Kent, UK
4 Institute of Postgraduate Medicine,Brighton & Sussex Medical School, University of Sussex, Brighton, East Sussex, BN1 9PX, UK
Journal of Orthopaedic Surgery and Research 2011, 6:59 doi:10.1186/1749-799X-6-59Published: 18 November 2011
This study will seek to identify a measurable radiographic index, the Metaphyseal-Diaphyseal Index (MDI) score to determine whether intra-operative fracture in osteoporotic bone can be predicted.
A 5 year prospective cohort of 560 consecutive patients, undergoing hemiarthroplasty (cemented or uncemented),
The Vancouver Classification was used to classify periprosthetic fracture.
The MDI score was calculated using radiographs from the uncemented group. As a control (gold standard), Yeung et al's
- Canal Bone Ratio
Cost analysis was also worked out for adverse outcomes.
Four hundred and seven uncemented and one hundred and fifty-three cemented stems were implanted. The use of uncemented implants was the main risk factor for intra-operative periprosthetic fracture.
Sixty-two periprosthetic fractures occurred in the uncemented group (15.2%), nine occurred in the cemented group (5.9%), P < 0.001. The revision rate for sustaining a periprosthetic fracture (uncemented group) was 17.7%, P < 0.001 and 90 day mortality 19.7%, P < 0.03.
MDI's AUC was 0.985 compared to CBR's 0.948, P < 0.001. The MDI score cut-off to predict fracture was 21, sensitivity 98.3%, specificity 99.8%, positive predictive value 90.5% and negative predictive value 98%. Multivariate regression analysis ruled out any other confounding factors as being significant.
The intra and inter-observer Pearson correlation scores were r = 0.99, P < 0.001.
JRI uncemented hemiarthroplasty has a significantly higher intra-operative fracture rate. We recommend cemented arthroplasty for hip fractures. We propose a radiographic system that may allow surgeons to select patients who are good candidates for uncemented arthroplasty, but it needs prospective validation.